Hi Yaang,
This is strange.
Could it be that you're migrating from SVN to Git? It can take hours for apps with a long history.
https://docs.mendix.com/developerportal/general/migrate-to-git/
That seems to be strange. Usually its a 2 mins process. I am not sure if it helps, but did you tried again today after rebooting your system? Or, just to be on a safer side, you can redownload the branch from the team server and try to upgrade it again freshly.